Optical scanners are well-known in the art and produce machine-readable data which is representative of the image of an object, e.g., a page of printed text. Optical scanners generally employ line-focus systems which image an object by sequentially focusing narrow "scan line" portions of the object onto a linear photosensor array by sweeping a scanning head over the object.
In a line-focus system, a light beam from an illuminated line object is imaged by a lens on a linear photosensor array which is positioned remotely from the line object. The linear photosensor array is a single dimension array of photoelements which correspond to small area locations on the line object. These small area locations on the line object are commonly referred to as "picture elements" or "pixels." In response to light from its corresponding pixel location on the line object, each photosensor pixel element in the linear photosensor array (sometimes referred to simply as a "pixel") produces a data signal which is representative of the light intensity that it experiences during an immediately preceding interval of time known as a sampling interval. All of the photoelement data signals are received and processed by an appropriate data processing system.
In a color optical scanner, a plurality of spectrally separated imaging beams (typically red, green and blue beams) must be projected onto photosensor arrays. Some color optical scanners employ beam splitter devices for spectrally separating an imaging light beam into color component beams. These separate color component beams are projected onto separate linear photosensor arrays. Other optical scanners project color component images on a single linear array in a series of separate scanning passes.
The construction and operation of color optical scanners employing beam splitter assemblies and photosensor arrays are disclosed in the following United States Patents: U.S. Pat. No. 5,410,347 of Steinle et al. for COLOR OPTICAL SCANNER WITH IMAGE REGISTRATION HOLDING ASSEMBLY; U.S. Pat. No. 4,870,268 of Vincent et al. for COLOR COMBINER AND SEPARATOR AND IMPLEMENTATIONS; U.S. Pat. No. 4,926,041 of Boyd for OPTICAL SCANNER (and corresponding EPO patent application no. 90306876.5 filed Jun. 22, 1990); U.S. Pat. No. 5,019,703 of Boyd et al. for OPTICAL SCANNER WITH MIRROR MOUNTED OCCLUDING APERTURE OR FILTER (and corresponding EPO patent application no. 90312893.2 filed Nov. 27, 1990); U.S. Pat. No. 5,032,004 of Steinle for BEAM SPLITTER APPARATUS WITH ADJUSTABLE IMAGE FOCUS AND REGISTRATION (and corresponding EPO patent application no. 91304185.1 filed May 9, 1991); U.S. Pat. No. 5,044,727 of Steinle for BEAM SPLITTER/COMBINER APPARATUS (and corresponding EPO patent application no. 91303860.3 filed Apr. 29, 1991); U.S. Pat. No. 5,040,872 of Steinle for BEAM SPLITTER/COMBINER WITH PATH LENGTH COMPENSATOR (and corresponding EPO patent application no. 90124279.2 filed Dec. 14, 1990 which has been abandoned); and U.S. Pat. No. 5,227,620 of Elder, Jr. et al. for APPARATUS FOR ASSEMBLING COMPONENTS OF COLOR OPTICAL SCANNERS (and corresponding EPO patent application no. 91304403.8 filed May 16, 1991), which are all hereby specifically incorporated by reference for all that is disclosed therein.
A hand-held optical scanning device is an optical scanner which is moved across a scanned object, e.g. a page of text, by hand. Optical systems for hand-held scanning devices must generally be very compact due to the relatively small size of hand-held scanning devices.
Rollers may be provided on a hand-held scanning device to guide the device across the object to be scanned and also to provide data to the scanning device microprocessor regarding the speed at which the scanning device is being moved over the scanned object. These rollers may also serve to control the speed at which an operator moves the scanning device across the scanned object.
The construction and operation of hand-held optical scanning devices employing such rollers is disclosed in United States patents: U.S. Pat. No. 5,381,020 of Kochis et al. for HAND-HELD OPTICAL SCANNER WITH ONBOARD BATTERY RECHARGING ASSEMBLY; U.S. Pat. No. 5,306,908 of McConica et al. for MANUALLY OPERATED HAND-HELD OPTICAL SCANNER WITH TACTILE SPEED CONTROL ASSEMBLY (and corresponding EPO patent application no. 94301507.3 filed Mar. 2, 1994), U.S. Pat. No. 5,723,859 of Kerschner et. al. for LINE CONTACT HAND-HELD SCANNING DEVICE AND METHOD HAVING A LIGHT PATH SUBSTANTIALLY PERPENDICULAR TO THE ORIENTATION OF THE OBJECT AT A LINE PORTION and U.S. Pat. No. 5,777,321 of Kerschner et al. for SCANNING DEVICE WITH NON-CONTACT OPTICAL COMPONENTS; which are all hereby specifically incorporated by reference for all that is disclosed therein.
In most hand-held optical scanning devices, the optical components and electronics of the scanning device are enclosed in a housing which is adapted to be grasped by the hand of a user while a scan is being performed. The housing generally also rotatably mounts the roller or rollers previously described.
In hand-held scanning devices, it is generally desirable to completely seal the portion of the housing enclosing the optical components and electronics. The housing, sealed in this manner, prevents dust, moisture and other potential contaminants from entering the interior of the housing and contaminating the optical components and associated scanning device electronics.
Because the image beam from the object must pass through the housing to reach the optical components, a sealed housing, as described above, must be provided with a transparent window. This window is generally attached directly to the bottom wall of the scanning device housing.
During use and transport of a hand-held scanning device, the housing of the device is often subjected to physical stress. One example of a cause of such physical stress is when a user of the scanning device squeezes the housing while performing a scan. Since the housing may be formed of plastic, which is relatively flexible, this stress may cause relative movement to occur between various portions of the housing and between the housing and the scanning device optical assembly. Because the window portion is generally attached to the housing, this relative movement also often results in relative movement between the window assembly and the optical assembly. It has been found that such relative movement often results in misalignment of the window assembly with the optical assembly and, accordingly, results in degradation of the light beam entering the optical assembly.
Thus, it would be generally desirable to provide an apparatus which overcomes these problems associated with hand-held optical scanning devices.